Can the fragmentation of hydrogen-bonded dimers be predicted: predissociation of C2H2-HX.

HX rotational state distributions following vibrational predissociation (VP) of C2H2−HX (X = Cl, F, O) dimers are predicted by expressing the predissociation process as the joint probability of rovibrational excitation in the fragments following “internal collision” in the vibrationally excited dimer. Calculations of these joint probabilities for the T-shaped dimers of acetylene with HCl, DCl, HF, and OH using the angular momentum (AM) method reproduce experimental distributions with reasonable accuracy. In dimers of this complex, many different pathways for the disposal of initial energy and momentum exist in principle. The use of simple physical arguments based on (a) the direction of initial impulse upon excitation and (b) restricted relative geometries due to limited amplitude of relative motion of the dimer components allows the number of effective dissociation pathways to be much reduced. For these, the probability of rotational and rovibrational transfer into the fragments is calculated, a process ...